Cable studied economics at Fitzwilliam College, Cambridge (B.A., 1966), and served for two years as treasury finance officer in Kenya before returning to the U.K. in 1968 as an economics lecturer at the University of Glasgow, where he received a Ph.D. in 1973. His political career was ignited in the 1970s in Glasgow, where he joined the Labour Party, served as a city councillor (1971–74), and became a close friend of and, briefly, adviser to John Smith, the future leader of the Labour Party. He served as an economist with the British government in the 1970s and with the Commonwealth Secretariat in the 1980s. In 1982, objecting to the leftward movement of the Labour Party and its concession of greater power to trade unions and grassroots organizers, Cable joined the newly formed Social Democratic Party. When the SDP merged with the Liberal Party in 1988, he became a Liberal Democrat. From 1990 to 1997 he worked for Shell Oil Company, ending his career there as its chief economist. In 1997 he was elected MP for Twickenham in West London, capturing the seat from the Conservatives.

Cable’s long experience as an economist in both the private and public sectors led to his selection as a Liberal Democrat spokesman on finance. He used his position to secure a major switch in party policy, away from higher taxes and higher public spending. In 2006 his fellow MPs elected him deputy leader. (When Sir Menzies Campbell suddenly resigned in October 2007, Cable spent two months as acting party leader.) Cable’s warnings that levels of personal debt were too high and the banking systems of the U.K. and U.S. were heading for trouble prompted many in his party to encourage him to run for leader, but he declined to stand and remained deputy leader under Nick Clegg. When the Conservative–Liberal Democrat coalition was formed after the May 2010 general election, Cable joined the cabinet and soon after resigned from his post as deputy leader.

As business secretary, he demanded, among other directives, that British banks curb their bonus payments to their highest-paid employees and that they revive lending to small businesses. He sparked criticism, however, when he broke his election campaign promises to not allow any increase in university tuition fees; once in office, Cable announced that fees would, in fact, be allowed to double because of the urgent need to cut government spending in an effort to restore balance to the U.K.’s public finances. In December 2010 he was stripped of all responsibility for media and telecommunications policy when he was secretly recorded “declaring war” on media mogul Rupert Murdoch over a proposed takeover of the satellite TV operator British Sky Broadcasting by Murdoch’s News Corp. In 2012, bolstered by public attitudes toward executive pay in the midst of the worldwide economic downturn, he called for more transparency and accountability in business, introducing a measure to Parliament that would allow for curbs on executive pay by giving shareholders a binding vote on executive salaries and bonuses. He was instrumental in the establishment of the U.K. Green Investment Bank, a government-funded project created to encourage private sector investment in sustainable, energy-efficient infrastructure, manufacturing, and jobs.

In the 2015 U.K. general election, Cable narrowly lost his seat to the Conservative candidate, Tania Mathias. In the June 2017 snap election, however, he was returned to Parliament, and in July he replaced Tim Farron as leader of the Liberal Democrats.